TX OUT does not come on until all the T/R switching is complete. This
guarantees that when TXEN is returned, all is well to transmit.
Carl Moreschi N4PY
121 Little Bell Drive
Hays, NC 28635
www.n4py.com
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Sunday, December 13, 2009 3:33 PM
Subject: Re: [TenTec] OmniVI: question about T/R control logic
Hi Allan,
You are correct about much of the logic going on inside
microprocessor chips in the Omni VI. Yet there is still a lot of T/R
control logic going on is simple resistor/transistor/diode circuitry in
the Omni VI, and a lot can be learned from the schematics.
My best guess it that "keying" the key or PTT input of the Omni VI
does all of the antenna switching and receiver muting stuff BEFORE the
TX EN signal comes back from the amplifier to say "Ok everything is
ready, now you can really transmit" I do not suggest risking equipment
damage, or hearing loss, based on a guess though. One way to confirm
what happens in what order would be to use a dual trace oscilloscope.
One input could be the PTT or Key input. Then you could probe around
other places, with and without the TX OUT and TX EN jumper in place, and
determine the time relation between keying input and PIN diode
switching, and the dependency (or not) of the TX EN signal.
DE N6KB
Allan Taylor wrote:
I now have a pair of OmniVIs and would like to use them in a sort of
poor-man's SO2R. Actually I
believe what I want to do is called SO2V but will actually be with two
radios. What I would like to do
is to have both radios functional on receive, and have the alternate
radio's (radio B) T/R PIN diode switch activated when the primary
radio(radio A) is transmitting, thus protecting the front end of the
alternate radio (radio B). Thus the question: Does the PIN diode
switch activate a) when the key is pressed/entered, b) when the signal
from the QSK loop / amp is returned, or c) at some other time. The
easiest solution would be to use radio A's QSK loop in some way to
activate radio B's T/R PIN switch. As the control logic is inside a
chip rather than in hardware, staring at the schematic does no good.
Any takers for this question??
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